Process of producing multicolor images



Patented Apr. 20, 1943 PROCESS OF PRODUCING MULTICOLQR 'DIAGES Bla Gaspar, Brussels-Forest, Belgium, assignor to Chromogen, Incorporated, a corporation of Nevada No Drawing. Application January 9, 1940, Serial No. 313,121. In Great Britain December 9,

11 Claims.

The present application is in part a continuation of my co-pending application Ser. No. 243,886 filed December 3, 1938 and subject matter claimed herein has been described in said prior application.

The invention relates to the production of multicolor pictures in a multilayer photographic material, by processes in which colored part pictures representing the various color separations are obtained successively in different layers through the effect of various treating baths. In processes of this kind it is necessary to restrict to certain layers the action of the treating baths employed to produce differently colored images. In order to restrict the effect of the bath'to the layer or layers it is destined to affect, there are 1 in which the part-images are recorded, and these intermediate layers are hardened or tanned after one layer has received its final color and before another layer is finally colored. By means of special composition or sensitizing, the intermediate layers of the original multilayer material are rendered capable of being selectively hardened in the course of the process of obtaining the multicolor image. To this end there are employed either a number of intermediate layers that are differentially sensitized for various ranges of infrared light, or one of the intermediate layers is sensitized for infrared light whilst the other intermediate layer is formed by a uniformly exposed or fogged silver halide emulsion.

Example 1.--A bipack exposure material is used the front element of which has a bluesensitive layer and a green-sensitive layer coated on the same side of a transparent support with the blue-sensitive silver halide layer next to the support and with the interposition of an inter mediate gelatin layer which contains the dye Milling Yellow G (Schultz Farbstofftabellen, Leipzig 1931, 7th ed.-, vol. 1, No. 726), 0.5 grm. per sq. m., and an amount of exposed silver bromide emulsion, the quantity of which can be determined by an experiment and which is in an excess to the amount required for decolorising the layer when treated for about three minutes with a 5 per cent solution of hydrobromic acid. The rear film of the bipack carries an ordinary red-sensitive film. The bipack is exposed through the support of the front element, developed and fixed. Thereafter, the front element is dyed by soaking it in a blue dye solution, for

example, a 1% solution of Pontamine Sky Blue stroyed at the places of the silver deposit by treating with an acid thiocarbamide solution or with hydrobromic acid, so that two blue colored,

images are obtained in the light-sensitive-layers whereas thedye is destroyed totally in the filter layer. The remnant silver is bleached with a bleacher containing potassium bichromate, for example, one of the following formula:

Potassium ferricyanide g 37.5 Potassium bromide g 56.25 Potassium dichromate g 37.5 Acetic acid cc 10 Water cc 2000 Potassium alum, 5% solution cc 1000 The bleacher simultaneously acts to an, the gelatin. The film is fixed with hypo and dried and thereafter treated with a 3% sodium hydrosulphite solution which acts to decolorise the blue dye image at the unhardened points ofthe upper layer but which is prevented from reaching the second light-sensitive layer by the uniformly hardened gelatin of themiddle layer. The decolorised outer layer still contains the tanned relief corresponding to the original silver image and the unhardened places can be colored by a water soluble dye. l

Example 2.The multilayer material exposed to the object comprises three silver halide emulsion layers for the production of color separation images, one layer being sensitized for blue, the

others for green and red respectively. .The blue- .tized for red and the rear layer for greenwithout a filter dye in the layer between. The exposure to the object is effected in a camera, infrared light being excluded.

The exposed film is developed but not fixed, the result being that black silver images are obtained in the three layers sensitized for blue.

green and red respectively while the pre-exposed intermediate layer shows a uniform blackening. The whole film is colored with a dye, the color of which. depends on the color to be given to the benzoethtgriln GL,

color selection record in the rear layer. If this layer was sensitized for red light and if it is desired to produce a positive in the correct colours the whole film is dyed blue-green for example by Brillant Benzo Fast Green GL (Brillant- Schultz Farbstoiftabelien, Leipzig 1939, 7th ed., Supplement II, P ge 131), and if the rear layer was sensitized for" green light the whole him is dyed magenta, for example by Diamin Fast Pink B (Diaminechtrosa 1B, SchultzFarbstoiftabellen. Leipzig. 1932, 7th ed., vol. 2, page 69) or Benzopurpurine 10B (Schultz Farbstoiftabellen, No. 489). The whole fllm'is then exposed to intense infrared light and subsequently developed in a tanning developer, such as a pyrocatechin developer without sulphite that simultaneously hardens and blackens the infrared-sensitive intermediate layer. The whole film is then fixed and then immersed in an aqueous solution containing about 3% sodium hydrosulphitewhich destroys the dye in the outer layers but which is prevented from penetrating into the rear-layer by the hardened intermediate layer;.the treatment may thus easily be determined as soon as the outer layers have become colorless. These decolorized layers are then permeated with a different dye, either by immersion in a bath of magenta, such as 'Iuchechtbrillantrot 2B (Schultz Farbstofftabellen, Leipzig 1932, 7th ed., vol. 2, page 221) or of bluegreen dye, such as Pontamine Sky Blue 53X (Schultz Farbstofftae bellen, Leipzig 1931, -7th ed., vol; 1, No. 513) according to whether the rear layer was dyed bluegreen or magenta. The hardened intermediate layer herealso prevents the penetration of the dye into the rear layer already-dyed and the process of dyeing is terminated as soon as the outer layers are uniformly colored. The dyes in all layers are then locally destroyed at the areas where silver is present by treatment with an acid thiocarbamide solution or with a diluted solution of hydrobromic acid, e. g. a solution of hydrobromlc acid with a content of 0.01% 2-oxy-3-aminophenazine. The treatment is continued until the dye-destroying solution has penetrated through the. hardened intermediate layer and the dye has been locally destroyed in the rear layer as well as in the outer layers. In view oi the delayed action of the dye-destroying solution in the rear layer, it is to be recommended that the dye employed for coloring this layer be of such a nature that it is easier bleached out than the dye used for coloring the outer layers, or there may be a catalyst incorporated in the emulsion employed for the rear layer before it is coated on the support, so that the destruction of the dye in this layer is accelerated. A-catalyst of this kind is 3,3'-carbonyl-bis-[2-oxy-3-aminol phenzanine]. The silver still present is converted into a silversalt that may be fixed out and for this purpose a tanning bleacher is employed, e. g.

Potassium ferricyanide -g 37.5 Potassium bromide g 56.2 Potassium bichromate g 37.5 Acetic acid cc 10 5% solution of potassium alum oc 1000 Water cc.' 2000 This bleaching bath hardens the gelatin at the same time, so that the uniform silver deposit Leipzig 1931, 7th ed., vol 1.

tion, dried and treated with a 3% aqueoussolution of sodium hydrosulphite. This destroys the dye at the areas in the surface layer that have not been hardened, but is prevented by the uniformly tanned intermediate layer from penetrating into the middle layer and thus destroying the dye therein. The, decolorized surface layer contains a mordanted relief that is capable of absorbing dye solutions at the areas not affected by light and these areasare dyed by immersion in a yellow dye solution, such as a solution of Chrysophenine ,G (Schultz Farbstofftabellen, Leipzig 1931, 7th ed., vol. 1, No. 726). The intermediate layer prevents the yellow dye from penetrating into the middle layer. The result of the processing is that a correctly colored posi- 'tive three-color-picture is obtained.

Example 3.- Alternatively, the three layers used in Example 2 may be coated on a transparent i latter is re-dyed blue-green.-

support in such a manner that the blue-sensitive layer is immediately adjacent to the support; then follows the first intermediate emulsion layer sensitive to infrared, then the green-sensitive layer, follower by the intermediate layer containing exposed silver halide, and finally by the red-sensitiveemulsion layer which in this case is'the surface layer. The exposure is, effected through'the support. The support itself contains a substance absorbing infrared light or this substance may be in a colorless or slightly colored colloid layer coated on that side of the support that isopposite to the light-sensitive emulsion layers. The object of this measure is torender the film capable of being exposed in the camera without any further precautions against the penetration of infrared light into the light-sensitive layers during exposure. When a multilayer film of this nature is employed, the sequence of dyeing is to be reversed, i. e. the three layers are all to be dyed yellow first and then the film is exposed to infrared light and again developed with the hardenlng'developer. After the two outer layers have been decolorized, they are re-dyed magenta andflnally, after decoloring the surface layer, the The exposure to infrared light of the intermediate layer that is to be tanned is effected from the side away from the infrared-absorbing support. 1 g

If, on the contrary, it is a question of printing material, in the course of whose exposure the exclusion of infrared light presents no particular difficulty, the reversed order of the layers similar to that described in second example, has the advantage that even an opaque, e. g. paper, support with a protecting varnish.

The essence'of the invention is the employment in a light-sensitive material of the intermediate layers and moreparticularly of intermediate layers which are uniformly exposed or which may be uniformly exposed owing to their being sensitive to infrared light. Such intermediate layers are not exposed at the same time as the layers destined to record the color-selection images, but are afterwards exposedto a uniform light and developed by a tanning process to serve as a protective intermediate layer during the treatment in the baths employed to produce the colored part-images. In a somewhatv similar manner the pre-exposed or fogged intermediate layers yield a protection layer when bleached with a tanning bleacher. The colored part-images may be obtained in various ways of which the example given above illustrates but one form not intended to limit the scope'of the invention. ,In order to mention a difierent coloring process the so-called.

colored development may be used for the illustration of which the following example, describing for the sake of simplicity a two-color-process, may be given.

Example 4.'I'wo differently sensitized layers are used with an infrared-sensitive intermediate layer between them. The film after having been e posed to a colored object withthe exclusion of infrared light is developed with a developer of the kind which simultaneously and in situ with the silver image gives an azo-methine dye. The film is uniformly and thoroughly exposed to infrared light and developed by a tanning developer. Thereafter, the dye in the surface layer is decolorized by an acid solution and the film illuminated by white light. This renders the silver halide developable and now the film is developed by a color developer yielding a different dye. The silver and silver halide is removed by Farmers reducer and a two-color-image is obtained in which the surface layer contains a colored positive record of one color sensation and the lower layer a diiferently colored negative record of a second color sensation. By printing and an analogous treatment a two-color-positive can be obtained.

What is claimed is:

l. A process of producing multicolor images from an exposed light-sensitive multilayer material having a support and at least three gelatin layers in superposition on said support, two of said layers containing latent photographic image records constituting two different part images of the multicolor image and one of said layers being an infrared-sensitive intermediate silver halide emulsion gelatin layer between said two layers, which comprises developing the latent images with a color developer which act to form the same azo-methine dye within the imagebearing layers, exposing the material to infrared light and developing the exposed silver halide with a tanning developer which acts to tan the gelatin in situ with metallic silver formed within the intermediate layer and thereafter decolorizing the dye image within the outer layer, exposing the iilm to white light, developing the outer layer with a color developer yielding a different color and removing the silver from said image-bearing layers and from said intermediate layer.

2. A process of producing multicolor images from an exposed light-sensitive multilayer material having a support and at least three gelatin layers coated on one side of said support, two of said layers containing developed silver image records constituting two different part images of the multicolor image, both image records being dyed the same color with a destructible dye and one of said layers being an intermed ate layer between said image-bearing layer which contains an evenly distributed substance including silver, which comprises treating the material with a tanning solution which acts in conjunction with said evenly distributed silver substance to tan the intermediate layer uniformly, and thereafter treating the outer layer with a solution to completely destroy the dye therein, and forming a dye image of a different color in proportion to the photographic image record contained in said outer layer.

3. A process of producing multicolor images from an exposed light-sensitive multilayer material having a support and five gelatin layers in superposition on said support, three of said gelatin layer between the two outer image-bear-.

ing layers containing uniformly exposed silver halide, .and another being an intermedlate layer between said image-bearing layers and thethird image-bearing'layer comprising infrared-sepsi tive silver halide, which comprises coloring all of the image-bearing layers with the same-destructible dye, exposirm the material with ini'ra-.

red light and treating the material'with-a tanning developer which acts to tan the gelatin in situ with the developed silver to therebysztan the last-mentioned intermediate layer uniformly,

treating the two outer layers with a solution to completely destroy the "dye therein, forming dye images of a different color in proportlomto the;

photograph'ic image records contained; in; said two outer layers, treatingthe material with a tanning bleacher, treating the outermost of said. 7

image bearing layers with a solution .tO completely destroy the dye therein," forming a dliferently colored image in proportion..:to the photographic image record contained in said outermost layer and removing thesilver from said image bearing layers and from said in ter-' mediate layers. i

4. A process of producing multicolor images from an exposed light sensitive multilayer'. mate-- rial having a support and at least three gelatin layers coated on one side of said support, two

of said layers containing developed silver image Y records constituting two different part images of the multicolor image and one of said layers being.

thereafter treating the outer layer with a solution to completely destroy the dye therein, and

"forming a dye image of a different color in proportion to the photographic image record contained therein.

5. A process of producing multicolor images from an exposed light sensitive multilayer material having a support and at least threegelatin layers'coated on one side of said. support, two of said layers containing developed silver image records constituting two difl'erent part images of the multicolor image and one of said layers being an intermediate layer between-said two layers which contains an evenly distributed substance including silver, which comprises coloring said two layers with the same destructible dye, treating the material with a tanning solution which acts in conjunction with said evenly distributed silver substance to tan the intermediate layer uniformly. and thereafter treating the outer layer with a solution to completely destroy the d e therein. forming a dye image of adifferent color in proportion to the photographic image record contained in said outer layer, the photoraphic image in said underlying image layer being converted to a dye image by destroying said destructible dye in proportion to said photographic image at a point insaid process following the coloring of said two layers.

6. A process of producing multicolor images from an exposed light-sensitive multilayer material having a support and at least three gelatin layers coated on one side of said support, two of said gelatin layers containing developed silver image records constituting two different part images of the multicolor image and one of said layersbeing an intermediate layer between said with a water soluble dye to color the unhardened places. I

9. A, process of producing multicolor images from an exposed light-sensitive multilayer matetwo layers which contains uniformly distributed metallic silver, said intermediate layer being colored by a dye which can be bleached in the pres-,

ence of metallic silver, which comprises uniformly coloring the image-bearing layers and the intermediate layer with :a dyewhich can be bleached in the presence of metallic silver,treatfrom an exposed light-sensitive material havin a'su'pport and at least three gelatin layers coated on one side of said support, two of said gelatin layers containing developed silver image records constituting two different part images of the multicolor image and one of said layers being an intermediate layer between said two layers which contains uniformly distributed -metallic silver, which comprises uniformly coloring the rial having asupport and at least three gelatin layers coated [on one side of said support, two of said layers containing developed silver image records constituting two different part images of the multicolor image and one of said layers. being an intermediate layer between said two layers which contains uniformly exposed and developed silver halide, whichcomprises uniformly coloring the image-bearing layers and the intermediate layer with the same dye which is capable of being destroyed with the aid of metallic silver. treating the material. with a dye-destroying agent which acts to destroy the dye where silver i present without entirely eliminating said silver, thereafter treating the material with a tanning bleacher which acts to tan the gelatin in situ with metallic silver and simultaneously to convert the silver into silver salt, and thereafter treating the surface layer with a solution to completely destroy the dye therein, forming a dye image of a different color in proportion to the image record contained in said surface layer, and

removing the silver salt from said image bearin layers and from said intermediate layer.

image-bearing layers and the intermediate layer witha dye which can be bleached in the presence of metallic silver, treating the-material with a"dye-destroying agent which acts to decolorize the parts where silver is present without entirely eliminating said silver, treating the material with a solution'which acts to transform the remaining silver into silver salt and simultaneously to tan-the gelatin where silver is present, treating the surface layer of said material with a dye-destroying solution which acts without the intermediate of silver and thereafter treating the decolorized'surfa'ce'layer to convert the tanned relief to a colored image Y 8. A process of producing multicolor images from an exposed light-sensitive multilayer material having a support and at least three gelatin layers coated on one side of said support, two

of said layers containing developed silver image re ords constituting two different part images or. the multicolor image and one of said layers being an intermediate layer between said two la ers which contains uniformly distributed meall c s lver. sa d intermediate layer being colored bv a dye which can be bleached in the presence o metallic silver, which comprises uniformly, colo ing the image-bearing layers and the intermediate layer with a dye which canbe bleached in the presence of-metallic silver, treating the material with a dye-destroying agent which acts to decnlorize the parts where silver-is present ithout entirely eliminatingsaid silver, treating he ma terial with a solution which acts to transform the remaining silver into silver salt and s multaneously to tan the gelatin where silver is present, fixing the film and drying, treating the surface layer with r a dye-destroying solution which acts without the intermediate of silver and thereafter treating the decolorized surface layer 10. A' process ofproducing multicolor images "from an exposed light sensitive multilayer material having a support and at least three gelatin layers coated on one side of said support, twoof said layers containing developed silver-image records constituting two different part'images of the multicolor image and one of said layers being an intermediate layer between said two layers which contains an evenly distributed substance including silver, which comprises coloring said two layers with the same destructible dye, treat ing the material with a tanning solution which acts in conjunction with said evenly distributed silver substance to tan the intermediate layer uniformly, and thereafter treating the outer layer with'a solution to completelydestroy the dye therein and forming a dye image of a different color in proportion to the photographic image record contained in saidouter layer.

ii. A process of producing multicolor images from an exposed light-sensitive multilayer material havinga support and at least three gelatin layers coated on one side of said support, two of said layers containing latent silver halide image records constituting two different part images of the multicolor image and one ofsaid layers being an infrared-sensitive intermediate silver halide emulsion gelatin layer between said two layers, which comprises developing the latent image with a color -developer which acts to form the same azo-methine dye within the image-bearing layers, exposin the material to infrared light and developing the ex osed silver BELA Gasma- 

